Increased Tear Fluid Production as a Compensatory Response to Meibomian Gland Loss: A Multicenter Cross-sectional Study

Abstract

To compare tear film parameters as well as meibomian gland morphologic features and function among patients with meibomian gland dysfunction (MGD), those with non-Sjögren syndrome aqueous-deficient dry eye (non-SS ADDE), those with non-SS ADDE and MGD, and normal subjects. Multicenter, cross-sectional, observational case series. Forty-one eyes of 41 patients (all women; mean age ± standard deviation, 62.1±9.9 years) with non-SS ADDE, 70 eyes of 70 patients (all women; 66.0±8.7 years) with MGD, 17 eyes of 17 patients (all women; 72.4±7.8 years) with non-SS ADDE and MGD, and 70 eyes of 70 normal control subjects (all women; 65.0±7.1 years). Ocular symptoms were scored from 0 to 14 and lid margin abnormalities from 0 to 4 according to their respective number. Meibomian gland changes were scored from 0 to 6 (meiboscore) on the basis of noncontact meibography findings, and meibum was graded from 0 to 3 depending on its volume and quality. Conjunctival and corneal epithelial damage were scored from 0 to 9 (fluorescein score). Tear film break-up time (TBUT) was measured as an index of tear film stability, and tear fluid production was evaluated with Schirmer's test. Ocular symptom score, lid margin abnormality score, meiboscore, meibum grade, fluorescein score, TBUT, and Schirmer's test value. The ocular symptom score did not differ significantly between the MGD and non-SS ADDE groups (P = 0.762). The lid margin abnormality score, meiboscore, and meibum grade were significantly higher in the MGD group than in the non-SS ADDE group (P = 0.0012, P < 0.0001, and P < 0.0001, respectively). The fluorescein score, TBUT, and Schirmer's test value were significantly worse in the non-SS ADDE group than in the MGD group (P < 0.0001, P = 0.0061, and P < 0.0001, respectively). The meiboscore correlated significantly with Schirmer's test value only in the MGD group (ρ = 0.508, P = 8.3×10(-6)). An increase in tear fluid production likely compensates for loss of meibomian glands in individuals with MGD.